K.E.
My first son was had colic and I did switch to Gentlease, and it made a little bit of a difference in his fussiness. I honestly don't remember whether he ate more or not. It's going to take some time though. It may take up to a week for your son to get used to the new formula. Imagine if all you ever ate or drank was coke, and then all of a sudden someone made you start drinking diet coke; they are basically the same, but there is a noticeable difference in taste and it will take a few days to get use to. If you still have some of his old formula left make his bottles with half the old stuff and half the Gentlease for a day or two, then switch to all Gentlease, doing this really made the transition easier for my son. I hope this helps!